Range finder



weh 2, 146 E, H, LAND RANGE FINDER Filed March 2, 1943 FIGJ I 'Patented Mar. 26, 1946 UNITED sTATss PATENT y orFici-z.

. RANGE FINDER Edwin H. Land, Cambridge, Mass., assigner to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Application March 2, 1943, Serial No. 477,708

9 claims. (ci. :sa-2.6)

This invention relates to a new and improved range finder and reticle system therefor.

It is one object of the invention to provide a new and improved range iinder comprising means for impressing optical 'indicia upon the ileld of view and comprising also means for bringing said produced by means of a pair of reticle marks positioned in side-by-side relation in the optical system of the device, wherein means .are provided for insuring that each eye of the observer see only one of said reticle marks, thereby giving a lstereoscopic eiect to'said indicia, and wherein means are provided for producing and controlling relative lateral motion of said reticle marks to cause said stereoscopic indicia to appear to move with respect to the eld of View.

A further object i's to provide a range iinder of the above characteristics wherein light-polarizing y means are used to insure that each eye of the observer see only one of said reticle marks, and

particularly wherein each of said reticle marks y comprises a dichroic light-polarizing image having its' axis perpendicular tothe axis of the lightpolarizing image constituting the other reticlemark.

Additional objects and advantages will in part fiecting surfaces I2 adapted to receive light from in front of the instrument through the Windows or apertures at I4. This arrangement serves both to provide an effectively enlarged interocular distance or increased stereoscopic effect, and' also to limit the field of view to an area substantially in front of the instrument. Associated with' mirrors I2 is a pair of transparent mirrors i5 each of which. is adapted to receive light from one ci' mirrors I2 and to reect it toward one of eyspieces I6. -f

An observer employing thi range iinder will look simultaneously through both of eyepieces I6 with the resultthat his right eye will receive light from. right-hand mirrors I2 and I5, and his left eye will simultaneously receive light 'from vleft-- hand" mirrors I2 and I5. It is to be understood that mirrors I5 and mirrors I2 should be so positioned as to enable an observer employing the instrument to see substantially the same field with each eye. Such a; structure, except for the use of transparent mirrors vI5 instead of wholly reecting surfaces, is standard in tlie construction of range finders of the class of the present invention. Its effect and purpose-is to increase the eiective interocular distance of the observer by the distance between mirrors I2, and thus to increase considerably the'stereoscopic acuity of his vision as applied to the eld.

appear and in part be pointed out in thevcourse of the following description of one or more embodlments f the invention, which are given as non-limiting examples, in connection with thev accompanying drawing, in which:

Figurev 1 is a plan view of a housing suitable vfor a range finder constituting an embodiment of the invention;

' Fig. 2 illustrates diagrammatially and :in plan the optical elements employed in one embodiment of the invention;

Fig. 3 is an enlarged diagrammatic view in perspective, partly broken away, illustrating cer-f;

diagrammatically a modication of the invention.-

In the form of the invention illustratedjin the tively large lens 25 or other device for colllmating The form oi an indicia-forming system suitable for use in the invention` is illustrated in detail in Figs. 2 and 3, vand may conveniently be located within an extended portion I8 of vhousing Ill. It comprises a light source 20 of any desired type, a pair of retlcles 22 and 24` of particular characteristics described in detail hereinafter, a relathe rays emanating from source 20 and traversing reticles 22 and 24, and a pair of light-polarizing elements 26 and 28. The term ret-lele, as it is used herein and in the claims, is to be understood as having the meaning commonly accorded thereto in the range nnder art, and it is to be considered as including any means for producing visible indicia such, for example, as a line, a dot.

vor a circle or other figure in the optical system of the instrument.

In the preferred embodiment'of the present infaxis of. the image comprising the other of said drawlngmousing I0 of any desired vsize and shape is vprovided'witna Ypair of mirrors or other repair of-reticles. These images may be produced in anyway known to theart.. For example, reticle parent hydrophilicmater'ial, such as polyvinyl alcohol, having the molecules on at least one sur- -face thereof predeterminedly oriented as indicated by arrow 32and having a suitable mark A on said surface by means ofany suitable dichroic dye orxstain, such for example as a solution containing iodine and an iodide. Reticle 24 may in turn comprise a-similar plastic sheet 33 having theA molecules on at least one surface thereof oriented at right angles to the molecules of sheet 32, as illustrated by arrow 34, and having a corresponding mark A' reproduced on said surface in the same manner as mark A on sheet 30. Preferably said marks will be on the adjacent faces of sheets 30 and 33 in order that they may lie substantially in the same plane. It will be under-' stoodthat said marks constitute respectively the rightand left-'eye images of a stereoscopic pair,

the functionof which in the instrument will vnow be explained. Y

Reticles 22 and 24 are positioned within the instrument in such manner that the reticle marks e 2,897,273 I n e 22 may comprise a sheet 30 of a suitable trans-` positionoutside housing I 0 where a knob 40 may l,

be readily manipulated by the operator of the instrument. It will, of course-be understood that shafts 36 and 38 rotate without lengthwise motion. l

It vwill be seen that with the above arrangement, as the operator rotatesknob 40, reticle` 22 will move' laterally with respect to reticle' 24 and willthereby cause mark A to move with respect to mark A. This will in turn cause theI stereoscopic image formed by the two images to appear to move in space towards or away from the ob\ .servers When said marks are directly superim- The relation between the apparent position of l the reticle image and the field depends largely upon the angular relation of mirrors I 2 and- I5 and upon the baseline of the instrument, i. e. the disltance between mirrors I2. If mirrors I5 are at vright anglessto each other and parallel to their thereon lie substantially within the focall plane of lens 25. Polarizing elements 26 and 28 func tion-as analyzers to insure that each eye of the observer see only one of saidV reticles. In the arrangement shown in Fig. 3, reticle 22 will form perimposed upon the eld seen by means of mirrors I2 and I5, and its apparent distance in the field from the instrument will depend upon the lateral distance between marks Ay and A'.

It should be understood that reticles 22 and 24 may take manyiforms. For example, in a preferred case, marks A and A' may comprise nonpolariaing outlines in otherwise uniformly lightpolarizing sheets, and in this case the stereoscopic reticle image will apear as an outline of light superimposed on the field. Another example may comprise the converse of this case, with said marks formed as light-polarizing outlines in other non-polarizing sheets, and in this case the stereoscopic image will appear as a black outline superimposed upon the field.A In either of said examples, said marks may comprise solid areas rather than outlines, and many further alternatives'will be apparent to those skilled in the art. It will be apparent that r'so long as the physical Krelation between lreticle marks A and A remains Athe same, the stereoscopic reticle image will appear to lie at the same .distance from the instument.- Therer are, therefore, preferably provided means for varying the distance laterally between said marks and thereby altering the apparent distance of said stereoscopic image from the instrument, together with means for translating said variation to a measurement 'of .said apparent distance.

Reticles 22 and 24 are mounted in any suitable manner permitting relative lateral movement. For example, nut is securedin any suitable manner to one of said reticles, `for example, reticle 22, and isenlarged` by threaded shaft 38, which may in turn be coupled with shaft 38 by means of gears 42. Shaft 38 may extend to a inl associated mirrors I2, the. reticle mark will appear to lie at infinity when marksA and A are directly superimposed. If, however, mirrors I5' are at right angles toeach other and mirrors I2 are at an angle of less than 90 degrees-to each tion of direct superimposition of the two marks,

the stereoscopic image will appear to move further away from the instrument. -f y.

Fig. 3 illustrates scale means adapted to indif cate the range of the apparent position of the reticle image, saidmeans comprising pointer 44 fixed to knob and cooperating with scale 45 mounted in any; suitable way on or within housl -ing III. Scale 45 may. read in any desirable unit of measurement, for example yards, and should be soadjusted withI respect to pointer 44 that the range opposite the `pointer will be a maximum when reticle 22 is at the limit of its travel to the left in Fig. 3, and will bek a minimum when said reticle is at the limit of'its travel to the parent that there may advantageously'be a suiti right in Fig. 3. It will be understood that the calibration of scale 45 is determined both by the base line of the instrument and by the angular relationsvof mirrors I2 and I5. It willkalso be apable Vernier system between knob 40 and shaft -38 and/or pointer 44 in order to cause relatively slight motion of reticle 22 and pointer 44 with relatively greater rotation -of'knob 4U, thus mak- Y ing it possible to obtain a more sensitive scale.

In using the above. described embodiment oi tne'inventma che observer nrst preferably ad- *It is tobe understoodthat the present inven-V tionLisnot limited to the foregoing embodiment lusts the. range Afinder so that the stereoscopic reticle image is substantially lin line with an object in; the eld of view whos'j range 4it is desired t0 i determine. 'Said image will in al1 probability appear to be in a different plane from said ob-V lect, either in front of or behind it in space. The operator'then turns knob Ill until said image appears tovlie .in the same plane as the object whose rangel is being measured, andlie may then read said range directly from scale 45. y

thereof, but that on the contrary many Vmodications,` may be made ,within the principles,v` of the invention and without departing from the scope thereof. In particular, any of many forms of reticle systems may be used. The above-described embodiment'utlizing light-polarizing material is preferred by reason of the ease of operation thereof, but the uise of light-polarizing material is not essential to the invention. For example, reticles 22 and 24 may instead comprise opaque marks, for example vertical lines,`on transparent plates or sheets, in which case polarizers 26` and 28 may be eliminated and a suitable septum 50 or similar element may be employedto insure that each eye of the observer see only one of said reticles. Alternatively, a pair of relatively movable light sources, such for example Vas a pair of illuminated line iilaments, may be substituted for light source 20, in which" case reticles 22 and 24 and polarizers -26 and 28 lmay be eliminated, but septum 50 will preferably be employed. With any yof these modifications of the reticle system, modifications in the control apparatus shown in Fig. 3 may be necessary, but such modifications and changes willbe apv parent to those skilled in the art and are to be construed as coming within the scope hereof.

To a considerable extent the construction o1" the range finders of the present invention is defor measuring the distatnce from said range finder to the apparent position in the field of view termined by the purpose for which they are in tended. For example, mirrors I2 and I5 'are used as illustrated in Figs. l .and 2 for the purpose of increasing the-range of the instrument and its accuracy at increased ranges. However,

this construction may be modified if the instrument is designed for use at relatively shorter ranges, i. e. of the order of one hundred yards or less. For such short ranges it may be desirable to rely only upon the human interocular. and Fig. 4 illustrates diagrammatically a modification of the invention suitable for such use. One

eye of the observer is indicated at 5I as viewing the field through a single transparent mirror 52, and the reticlesystem comprises a light source 5d, reticles 55 and 56, a pair of light-polarizing elements 60 which polarize light oppositely, only one element of the pair of elements 60 being shown in Fig. 4, and lens 58. Many other modifications will doubtless be apparent to those skilled in the art and are to be construed as coming within the scope of the invention.

Since certain changes may be made in the above device, and different embodiments of the invenof the stereoscopic image formed by said reticle images. j

2. In a range finder, in combination, means for increasing the effective interocular of an observer,

images deiined by light-'polarizing material, the transmission axis of the material dei-ming one of said images being substantially perpendicular to that ofthe material defining the other said image,

meansifor superimposing said images upon the field of view, light-polarizing means for/substan-- tially blocking from each eyeV of an observer that image intended to be .seen by the other eye, and means for altering the lateral displacement of said reticles with respect to each other.

3. In a range finder, in combination, a pair of reticles providing righteye and left-eye images defined by light-polarizing material, the transmission axis lof the material defining one of said images being'substatntially perpendicular to that of the material defining the 'other said image,

means for s uperimposing said images upon th'.-

iield of View, means for substantially collimatiner the light carrying said images, light-polarizing means for substantially blocking from each eye of an observer that image intended to be seen by the other eye, and means for altering the lateral displacement of said reticles with respect to-each other. i

4. `In a range finder, in combination, a pair of reticles providing right-eyeand left-eye imagesy defined by light-'polarizing material, the transmission axis of the material d'ening one of said images being substantially perpendicular to 'that of the material dening the other said image,

images defined by light-polarizing material, the

tion could be made without departing from the scope thereof, it is'intended that all matter contained in the above description 'or shown in the accompanying drawing shal1 be interpreted as illustrative and not in a limiting sense.

It is also .to 'be understood that the'following claims are intended to cover all the generic andspecific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, mightv be said to fall therebetween.

What is claimed is:

1. In a range finder, in combination, a pair of reticles providing right-eye and left-eye images dened 'by light-polarizing material the transmission axis of the material deiining one of said images being substantially perpendicular to that of the material `deiining the other said image, means for superimposing said images upon the field of view, light-polarizing means for substantially blocking from each eye of an observer that image intended to be seen bythe other eye, means for altering rthe lateral displacement of said reticles with respect to each other, and 4scale transmission axis o f the material defining one of said images being substantially perpendicular to that of the material defining the other said image,

transparent mirror means for superimposing said l images upon the iield of view, lightapolarizing means for substantially blocking from each eye of an observer thatimage intended to be seen by the other eye, and means for altering the lateral displacement of said reticles with respect to each-other.

6a In a range finder, in combinatioma pair of intended to be seen by the other eye, and meansfor altering the lateral displacement of said reticles with respect to each-other.

7. In a range finden-in combination, means Afor increasing the effective interocular oi' an observer, a pair ofreticles providing right-eye and -left--eye images dened by light-polarizing mate# .Y rial, the transmission axis of the material defining one of said images being substantially perpendicu'lar lto that of the material defining the other saidv image, a collimating llens positioned between said reticles and an observer, said reticles being positioned substantially in the focal plane of said lens, means for superimposing saidirnages upon the eld of view, light-polarizing means forA substantially blocking from each eye of an observer that image intended to be seen by the other Va collimating lens positioned between said reticlesand an observer, said reticles being positioned substantially inthe focal plane of said lens, means for superimposing said images upon the iield of view.l light-polarizing means. -for substantially blocking from each eye of an observer that image intended to be seen bythe other eye, means for alteringv the lateral displacement of said reticleswith respect to each other, and scale means responsive to said last-mentioned means lfor measuring the distance from said range finder tothe apparent position in the field of view of the stereoscopic image formed by'said Ireticl'e images.

9. In a range iinder, in combination', binocular. .means for viewing an object to be ranged. a pair of reticles providing right-eye and leftfeye imagesl dened by light-polarizing material,v said reticles being arranged with respect to each other so that light polarized Vby one reticle is polarized in a sense opposite to light polarized by the'other reticle, beam-joiner means inthe path 'of rays proceeding from said object and in the path oi rays proceeding from said reticles for joining said rays and directing the combined rays towards the eyes of an observer using the range finder,

)night polarizing means in the path of rays proceeding from said reticles for substantially blocking from each eye of the observer that image intended to be seen by the other eye, and means for altering the lateral displacement ofv said reticles with respect to each other.

EDWIN H. LAND. 

